1. Field of the Invention
This invention relates to a start-up process for hydrorefining heavy hydrocarbonaceous oils.
2. Description of the Prior Art
Hydrorefining is a well-known process for upgrading a variety of hydrocarbon fractions. The term "hydrorefining" is used herein to designate a catalytic treatment in the presence of hydrogen, of a hydrocarbonaceous oil, to upgrade the oil by eliminating or reducing the concentration of contaminants in the oil such as sulfur compounds, nitrogenous compounds, metal contaminants and/or partial saturation of the oil.
U.S. Pat. Nos. 3,953,321 and 4,098,721 disclose a hydrodesulfurization process for heavy hydrocarbonaceous oils such as gas oils in which a conventional hydrodesulfurization catalyst is sulfided and heat treated at a temperature of 750.degree. to 850.degree. F. prior to initiating the hydrodesulfurization. The catalyst is sulfided by contact with a lighter boiling range oil (column 3, lines 59-68) or is heat treated in the presence of the lighter oil, free from sulfur (column 4, lines 14-19).
U.S. Pat. No. 2,954,339 discloses use of a spent cobalt-molybdenum-alumina catalyst for hydrodesulfurization of a hydrocarbonaceous oil which may be a gas oil. Prior to contact with the gas oil, the catalyst is used to hydrotreat naphtha.
U.S. Pat. No. 3,423,307 discloses a start-up method for a hydrodesulfurization process for heavy residual feeds which contain asphaltic materials. The catalyst is initially contacted with an asphaltic-free feed.
U.S. Pat. No. 3,528,910 discloses a hydrotreating process for hydrocarbonaceous oils. A catalyst, such as a supported nickel-molybdenum catalyst, is sulfided in the presence of hydrogen with a distillate containing disulfide sulfur prior to the hydrotreating reaction.
U.S. Pat. 4,149,965 discloses a start-up process for hydrorefining of naphtha. The catalyst is partially deactivated by treatment with a substantially non-metal containing hydrocarbon oil in the presence of hydrogen prior to contacting the catalyst with the naphtha feed.
U.S.Pat. No. 3,368,965 discloses a slurry hydrogenation process in which a catalyst, such as cobalt molybdate on alumina, is pretreated by wetting the catalyst with a clean (i.e. non-aromatic) hydrocarbonaceous oil such as a lubricating oil fraction to form a slurry which is then introduced into the hydrocarbonaceous oil to be hydrogenated.
It has now been found that by pretreating a sulfided hydrorefining catalyst with a light hydrocarbonaceous oil in the presence of hydrogen prior to hydrorefining the heavy hydrocarbonaceous oil feed, the initial activity of the catalyst can be increased.
All boiling points to which reference is made herein are atmospheric boiling points unless otherwise specified.
The Periodic Table referred to herein is in accordance with Handbook of Chemistry and Physics, published by the Chemical Rubber Company, Cleveland, Ohio, 45th Edition, 1954.